Ion implantation is a technique for introducing conductivity-altering impurities into a substrate such as a wafer or other workpiece. A desired impurity material is ionized in an ion source of an ion beam implanter, the ions are accelerated to form an ion beam of prescribed energy, and the ion beam is directed at the surface of the substrate. The energetic ions in the ion beam penetrate into the bulk of the substrate material and are embedded into the crystalline lattice of the material to form a region of desired conductivity.
In some ion implant processes, a desired doping profile is achieved by implanting ions into a target substrate at high temperatures. Heating a substrate can be achieved by supporting the substrate on a heated platen during an ion implant process. A conventional heated platen may be connected to an electrical power source via a plurality of electrical contact probes. Additional electrical contact probes may be connected to the heated the platen for enabling electrostatic clamping of a substrate.
During operation, the various electrical contact probes connected to a heated platen may absorb heat from the heated platen and may reduce the temperature of the heated platen in localized areas adjacent to the electrical contact probes. As will be appreciated, any temperature variations in the material of the heated platen may affect the uniformity of heat transferred to a target substrate supported and heated by the heated platen, potentially having an adverse effect on an ion implant process. In some instances, temperature variations in a heated platen can cause the heated platen to warp, bow, or even crack.
In view of the foregoing, there is a need to mitigate heat losses via electrical connections in heated platens in order to achieve uniform platen temperatures.